The American green kingfishers breed by streams in forests or mangroves, nesting in a long horizontal tunnel made in a river bank.

They have the typical kingfisher shape, with a short tail and long bill. All are plumaged oily green above, and the underpart colour shows an interesting pattern insofar as the smallest and second largest, American pygmy kingfisher and green-and-rufous kingfisher, have rufous underparts, whereas the largest and second smallest, Amazon kingfisher and green kingfisher, have white underparts with only the males also having a rufous breast band.

These birds take crustaceans and fish caught by the usual kingfisher technique of a dive from a perch or brief hover, although the American pygmy kingfisher]] will hawk at insects in flight.